95. POTAMOSBTONACBiB. 379 



cal and spongy beneath, roots solitary blunt. — S. B. 1233. R. 

 vii. 14. Teimatophace Schleid., Endl. — Fronds 1 — 2 lines long, 

 at first flattish, afterwards remarkably gibbous and cellular 

 beneath.— On stagnant -water. A. VI.— VIII. E. S. I. 



4. L. polyrrMza (L.) ; fronds roundisTi-obovate, compressed, 

 roots many clustered acute. — E. B. 2458. 2J. vii. 15, Spirodela 

 Schleid., Endl. — Fronds half an in. long, green above, purple 

 beneath. Fl. not seen in Britain. — Ou water. A. E. S. I. 



~~ 2. WoLFFiA HorJcel. 



1. W. arrJiiai (Wimm.) ; fronds very small suhglobular flattish 

 above cellular beneath, solitary, young frond separating imme- 

 diately from the old one.— «;/. E. B. 1398. R. vii. 14.— Frond 

 like a grain of sand, subglobular at all ages, green. Offset from 

 within the base of the old frond. — Ponds near London. A. B. 



Order XCV. POTAMOGETONACEiE. 



Fl. perfect or .imperfect. Perianth inferior, 4-parted, or 0. 

 Stam. free, 1 , 2, or 4. Ovaries 4, distinct, each with ] ovule 

 and 1 sessile stigma. Fr. a drupe enclosing a hard nut, or a 

 dry nut, not bursting, 1-seeded. Albumen 0. Embryo with a 

 thin skin having a lateral cleft. 



1. PoTAMOGBTON. Fl. perfect. Perianth 4-parted. Anth. 

 4, sessile, opposite to the divisions of the perianth. Ovaries 

 4. Styles 0. Drupes 4, sessile. — ^Fl. sessile, spiked. 



2. RuppiA. Fl. perfect. Perianth 0. Stam. 2, the cells 

 considerably separated; filaments very short, scalelike. 

 Ovaries 4. Styles 0. Nuts 4, with long stalks. — Fl. 

 about 2 together. 



3. Zannichbllia. Fl. monoecious, axillary. Barren with 

 1 stam., and no perianth. Fertile with a bellahaped 

 perianth, persistent style, and peltate stigma. Nuts 2-^5 

 or more, more or less stalked. 



1. Potamoge'ton Linn. Pondweed. 



* i. alternate, Jloi-all.^oaiing and sometimes opposite ; stipules 

 free. 



1. P. ndtans (L.) ; 1. all stalked, upper coriaceous floating 

 ovate or elliptic folded at the base, lower leafless petioles linear 

 or setaceous, fr. (large) rounded on the hack when fresh heeled 

 when, dry, peduncle equal. — E. B. 1822. R. vii. 60. — St. creep- 



